Since there seems to be some conflicting data and opinions being spread about M193 jackets lately, I decided to a quick evaluation.

I took one sample from a lot of Wolf Gold (Taiwan), IMI M193, and Federal Lake City XM193.  

The bullets were pulled and weighed.  All showed signs of tar sealant at the bullet.  This was cleaned off with a solvent to keep the bullet mass consistent with copper and lead only.

XM193:  54.7gr
IMI:        54.9gr
Wolf:      55.4gr








Note:  The jacket on the Wolf Gold is "rolled" into the base, making it appear thicker.  This is just a jacket design different and has no relationship to jacket thickness.



The bullets were measured for length:

XM193:  .738"
IMI:        .743"
Wolf:      .745"


Next, a jig was set up to melt the lead out of the jacket.  The copper was heated until it was glowing using a propane torch.  A visual inspection was done to ensure all lead was removed.




The jackets were then weighed for total jacket mass:

XM193:  17.4gr
IMI:        17.7gr
Wolf:      16.8gr

Note - that the Wolf Gold had the lightest jacket mass of the bunch.






The jackets where then cut in a cross section just above the cannelure.  Visual inspection shows no discernable difference in jacket thickness:




The jackets where then measured in 4 places to determine avg jacket thickness, which was very consistent:



XM193:  .0255"
IMI:        .024"
Wolf:      .023"










Conclusions:

Out of the three samples tested - Wolf Gold (Taiwan) has the lightest jacket, and the thinnest jacket out of all.  Federal XM193 had the thickest jacket at the location measured.  All of them were very close.



The real testing comes from ballistic gelatin testing, which should be available from another member soon.  However, this should serve as a valid data point with regard to the jacket thickness postulations.

Great post. Very informative.

good post thanks!

Excellent post, thanks for that information.  

So, any guesses as to ballistic performance based on this?  I'd guess the Wolf would more consistently fragment since it has a thinner jacket, but I really have no idea if there is any correlation.

this should settled the 'Wolf Golds jacket is too thick to fragment' argument

Good for you for sticking to your guns.

The IMI bullets always look so much more consistent than the others. I guess that's why I get better accuracy with them.

Wolf Gold outperforms IMI in accuracy in every test I have seen, including my own.

IMI M193 is the most accurate M193 I have, but what is odd, is that Q3131A is made by IMI under contract, and has performed very poorly for me in accuracy tests, as has "Independence 5.56" which is made by IMI for Federal.  That stuff is super hot, and has the worst accuracy of any M193 I have ever shot.

Also a word of thanks !

Thank You.

Good Job! Thanks for taking the time.

I'm going to go out on a limb here and say .0025" difference in jacket thickness is not going to make much difference.

What in my mind will make the difference will be the composition of the copper jacket. Pure copper with trace metals, the more trace metals the harder the jacket.

I imagine there is some formulation of pure copper with a percentage of trace metals that make the best jackets, not to hard not to soft.

Awesome post, thanks!

Solid work, thanks

Thank you for the great post.

Standard bullet jackets are made of "gilding metal," a brass alloy of 95% copper, 5% zinc.  It's pretty easy to see the difference in alloys that aren't in the close proximity of this mixture; the jacket will look a lot like cartridge brass (70% copper, 30% zinc).  

You do NOT want "pure copper" jackets, because copper corrodes pretty quickly.  That 5% zinc content keeps the copper from corroding (it will still tarnish), while hardening it just enough to keep its shape.

All three of those bullet jackets are essentially "gilding metal" with at least a 95% probability.  Jacket consistency, thickness, and how the jacket is heat treated during manufacture are all real factors, but hardness of the jackets due to the alloy is not an issue.

Excellent work. I wonder if more hollow base of the Wolf gold bullet helps its accuracy by acting like expanded base bullets to help seal and grab the rifling better.

In other words, those of us stacking Wolf Gold while it is still the cheapest are smart to do so.

Thanks for doing this test!

Rob

Great Info!  Thanks for taking the time to post.

Excellent post as others have stated.  I enjoyed reading.

Copper alloys used in projectiles aren't heat treated, other that the initial annealing of the raw sheet.

Any hardening will be due to the work hardening through the forming process. the difference in hardness would be next to nonexistant as the the amount of drawiing and forming is the same.



The only difference between the above and a FMJ is the lead slug is inserted in the back end of a FMJ and the closed end is swaged pointy instead of flat.

Great job, very informative.

Annealing the jacket sheet is often the only heat treat for closed base jackets.  On the other hand, some bullet makers do a second anneal after cupping, especially for pointed FMJ bullets because forming the nose sometimes causes issues.  The number of steps in the production of the jacket varies by manufacturer, including how many times the cup is annealed, and how many different cupping/drawing steps are used.  More draws means a harder jacket, more annealing means a softer jacket.

And together, all of those differences in production add up to a minimal difference between jacket A and jacket B.  That might make some difference in how well a bullet fragments, but not as much as jacket thickness and consistency.  I think whether or not the bullet has a cannelure has more to do with whether it will consistently fragment than how hard the jacket is.

The Wolf bullet's having a rolled base could contribute to better accuracy by presenting a more consistent base as the bullet leaves the muzzle.  Inconsistency there could be essentially similar to a damaged crown, with the muzzle gasses having a little more or a little less space to escape as the bullet clears.  That can cause bullets to wobble and be less stable.  Note that flat bases, or flat, boat tail based bullets are the typical form for match grade bullets...  That "cupped" base won't expand to seal the bore better - sealing the bore is a function of the jacketed bullet's diameter fitting the bore accurately.

Thank you for taking the time to do this and posting the results!

I'd be interested in seeing Prvi 193 included, though I suspect the results would be quite similar.

As well as Hornady 55gr. FMJ....

Very nice and as always ... nurturing, FAGARAK.

TRG

What a great post - thanks!   As mentioned, it would be awesome if you did a follow up test including a few more brands - Hornady in particular, since their 55 ball is considered the benchmark for a quality bulk 55 FMJ.


Interesting that the base of the IMI looks like ass, compared to the other 2.  Normally IMI is considered some of the best, but that smeared and uneven base sure doesn't look that great!